Commit | Line | Data |
---|---|---|
3fcfab16 AM |
1 | |
2 | #include <linux/wait.h> | |
3 | #include <linux/backing-dev.h> | |
03ba3782 JA |
4 | #include <linux/kthread.h> |
5 | #include <linux/freezer.h> | |
3fcfab16 | 6 | #include <linux/fs.h> |
26160158 | 7 | #include <linux/pagemap.h> |
03ba3782 | 8 | #include <linux/mm.h> |
3fcfab16 AM |
9 | #include <linux/sched.h> |
10 | #include <linux/module.h> | |
cf0ca9fe PZ |
11 | #include <linux/writeback.h> |
12 | #include <linux/device.h> | |
455b2864 | 13 | #include <trace/events/writeback.h> |
cf0ca9fe | 14 | |
c3c53206 JA |
15 | static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0); |
16 | ||
26160158 | 17 | struct backing_dev_info default_backing_dev_info = { |
d993831f | 18 | .name = "default", |
26160158 JA |
19 | .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE, |
20 | .state = 0, | |
21 | .capabilities = BDI_CAP_MAP_COPY, | |
26160158 JA |
22 | }; |
23 | EXPORT_SYMBOL_GPL(default_backing_dev_info); | |
cf0ca9fe | 24 | |
5129a469 JE |
25 | struct backing_dev_info noop_backing_dev_info = { |
26 | .name = "noop", | |
976e48f8 | 27 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
5129a469 JE |
28 | }; |
29 | EXPORT_SYMBOL_GPL(noop_backing_dev_info); | |
30 | ||
cf0ca9fe | 31 | static struct class *bdi_class; |
cfc4ba53 JA |
32 | |
33 | /* | |
34 | * bdi_lock protects updates to bdi_list and bdi_pending_list, as well as | |
35 | * reader side protection for bdi_pending_list. bdi_list has RCU reader side | |
36 | * locking. | |
37 | */ | |
03ba3782 | 38 | DEFINE_SPINLOCK(bdi_lock); |
66f3b8e2 | 39 | LIST_HEAD(bdi_list); |
03ba3782 JA |
40 | LIST_HEAD(bdi_pending_list); |
41 | ||
42 | static struct task_struct *sync_supers_tsk; | |
43 | static struct timer_list sync_supers_timer; | |
44 | ||
45 | static int bdi_sync_supers(void *); | |
46 | static void sync_supers_timer_fn(unsigned long); | |
03ba3782 | 47 | |
f758eeab CH |
48 | void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2) |
49 | { | |
50 | if (wb1 < wb2) { | |
51 | spin_lock(&wb1->list_lock); | |
52 | spin_lock_nested(&wb2->list_lock, 1); | |
53 | } else { | |
54 | spin_lock(&wb2->list_lock); | |
55 | spin_lock_nested(&wb1->list_lock, 1); | |
56 | } | |
57 | } | |
58 | ||
76f1418b MS |
59 | #ifdef CONFIG_DEBUG_FS |
60 | #include <linux/debugfs.h> | |
61 | #include <linux/seq_file.h> | |
62 | ||
63 | static struct dentry *bdi_debug_root; | |
64 | ||
65 | static void bdi_debug_init(void) | |
66 | { | |
67 | bdi_debug_root = debugfs_create_dir("bdi", NULL); | |
68 | } | |
69 | ||
70 | static int bdi_debug_stats_show(struct seq_file *m, void *v) | |
71 | { | |
72 | struct backing_dev_info *bdi = m->private; | |
c1955ce3 | 73 | struct bdi_writeback *wb = &bdi->wb; |
364aeb28 DR |
74 | unsigned long background_thresh; |
75 | unsigned long dirty_thresh; | |
76 | unsigned long bdi_thresh; | |
345227d7 | 77 | unsigned long nr_dirty, nr_io, nr_more_io; |
f09b00d3 JA |
78 | struct inode *inode; |
79 | ||
345227d7 | 80 | nr_dirty = nr_io = nr_more_io = 0; |
f758eeab | 81 | spin_lock(&wb->list_lock); |
7ccf19a8 | 82 | list_for_each_entry(inode, &wb->b_dirty, i_wb_list) |
c1955ce3 | 83 | nr_dirty++; |
7ccf19a8 | 84 | list_for_each_entry(inode, &wb->b_io, i_wb_list) |
c1955ce3 | 85 | nr_io++; |
7ccf19a8 | 86 | list_for_each_entry(inode, &wb->b_more_io, i_wb_list) |
c1955ce3 | 87 | nr_more_io++; |
f758eeab | 88 | spin_unlock(&wb->list_lock); |
76f1418b | 89 | |
16c4042f WF |
90 | global_dirty_limits(&background_thresh, &dirty_thresh); |
91 | bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); | |
76f1418b MS |
92 | |
93 | #define K(x) ((x) << (PAGE_SHIFT - 10)) | |
94 | seq_printf(m, | |
95 | "BdiWriteback: %8lu kB\n" | |
96 | "BdiReclaimable: %8lu kB\n" | |
97 | "BdiDirtyThresh: %8lu kB\n" | |
98 | "DirtyThresh: %8lu kB\n" | |
f09b00d3 | 99 | "BackgroundThresh: %8lu kB\n" |
f7d2b1ec | 100 | "BdiWritten: %8lu kB\n" |
f09b00d3 JA |
101 | "b_dirty: %8lu\n" |
102 | "b_io: %8lu\n" | |
103 | "b_more_io: %8lu\n" | |
104 | "bdi_list: %8u\n" | |
c1955ce3 | 105 | "state: %8lx\n", |
76f1418b MS |
106 | (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), |
107 | (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), | |
f7d2b1ec JK |
108 | K(bdi_thresh), |
109 | K(dirty_thresh), | |
110 | K(background_thresh), | |
111 | (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)), | |
112 | nr_dirty, | |
113 | nr_io, | |
114 | nr_more_io, | |
c1955ce3 | 115 | !list_empty(&bdi->bdi_list), bdi->state); |
76f1418b MS |
116 | #undef K |
117 | ||
118 | return 0; | |
119 | } | |
120 | ||
121 | static int bdi_debug_stats_open(struct inode *inode, struct file *file) | |
122 | { | |
123 | return single_open(file, bdi_debug_stats_show, inode->i_private); | |
124 | } | |
125 | ||
126 | static const struct file_operations bdi_debug_stats_fops = { | |
127 | .open = bdi_debug_stats_open, | |
128 | .read = seq_read, | |
129 | .llseek = seq_lseek, | |
130 | .release = single_release, | |
131 | }; | |
132 | ||
133 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) | |
134 | { | |
135 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); | |
136 | bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, | |
137 | bdi, &bdi_debug_stats_fops); | |
138 | } | |
139 | ||
140 | static void bdi_debug_unregister(struct backing_dev_info *bdi) | |
141 | { | |
142 | debugfs_remove(bdi->debug_stats); | |
143 | debugfs_remove(bdi->debug_dir); | |
144 | } | |
145 | #else | |
146 | static inline void bdi_debug_init(void) | |
147 | { | |
148 | } | |
149 | static inline void bdi_debug_register(struct backing_dev_info *bdi, | |
150 | const char *name) | |
151 | { | |
152 | } | |
153 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) | |
154 | { | |
155 | } | |
156 | #endif | |
157 | ||
cf0ca9fe PZ |
158 | static ssize_t read_ahead_kb_store(struct device *dev, |
159 | struct device_attribute *attr, | |
160 | const char *buf, size_t count) | |
161 | { | |
162 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
163 | char *end; | |
164 | unsigned long read_ahead_kb; | |
165 | ssize_t ret = -EINVAL; | |
166 | ||
167 | read_ahead_kb = simple_strtoul(buf, &end, 10); | |
168 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
169 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
170 | ret = count; | |
171 | } | |
172 | return ret; | |
173 | } | |
174 | ||
175 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) | |
176 | ||
177 | #define BDI_SHOW(name, expr) \ | |
178 | static ssize_t name##_show(struct device *dev, \ | |
179 | struct device_attribute *attr, char *page) \ | |
180 | { \ | |
181 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ | |
182 | \ | |
183 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ | |
184 | } | |
185 | ||
186 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) | |
187 | ||
189d3c4a PZ |
188 | static ssize_t min_ratio_store(struct device *dev, |
189 | struct device_attribute *attr, const char *buf, size_t count) | |
190 | { | |
191 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
192 | char *end; | |
193 | unsigned int ratio; | |
194 | ssize_t ret = -EINVAL; | |
195 | ||
196 | ratio = simple_strtoul(buf, &end, 10); | |
197 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
198 | ret = bdi_set_min_ratio(bdi, ratio); | |
199 | if (!ret) | |
200 | ret = count; | |
201 | } | |
202 | return ret; | |
203 | } | |
204 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
205 | ||
a42dde04 PZ |
206 | static ssize_t max_ratio_store(struct device *dev, |
207 | struct device_attribute *attr, const char *buf, size_t count) | |
208 | { | |
209 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
210 | char *end; | |
211 | unsigned int ratio; | |
212 | ssize_t ret = -EINVAL; | |
213 | ||
214 | ratio = simple_strtoul(buf, &end, 10); | |
215 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
216 | ret = bdi_set_max_ratio(bdi, ratio); | |
217 | if (!ret) | |
218 | ret = count; | |
219 | } | |
220 | return ret; | |
221 | } | |
222 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
223 | ||
cf0ca9fe PZ |
224 | #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store) |
225 | ||
226 | static struct device_attribute bdi_dev_attrs[] = { | |
227 | __ATTR_RW(read_ahead_kb), | |
189d3c4a | 228 | __ATTR_RW(min_ratio), |
a42dde04 | 229 | __ATTR_RW(max_ratio), |
cf0ca9fe PZ |
230 | __ATTR_NULL, |
231 | }; | |
232 | ||
233 | static __init int bdi_class_init(void) | |
234 | { | |
235 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
236 | if (IS_ERR(bdi_class)) |
237 | return PTR_ERR(bdi_class); | |
238 | ||
cf0ca9fe | 239 | bdi_class->dev_attrs = bdi_dev_attrs; |
76f1418b | 240 | bdi_debug_init(); |
cf0ca9fe PZ |
241 | return 0; |
242 | } | |
76f1418b | 243 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 244 | |
26160158 JA |
245 | static int __init default_bdi_init(void) |
246 | { | |
247 | int err; | |
248 | ||
03ba3782 JA |
249 | sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers"); |
250 | BUG_ON(IS_ERR(sync_supers_tsk)); | |
251 | ||
03ba3782 | 252 | setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0); |
6423104b | 253 | bdi_arm_supers_timer(); |
03ba3782 | 254 | |
26160158 JA |
255 | err = bdi_init(&default_backing_dev_info); |
256 | if (!err) | |
257 | bdi_register(&default_backing_dev_info, NULL, "default"); | |
976e48f8 | 258 | err = bdi_init(&noop_backing_dev_info); |
26160158 JA |
259 | |
260 | return err; | |
261 | } | |
262 | subsys_initcall(default_bdi_init); | |
263 | ||
03ba3782 JA |
264 | int bdi_has_dirty_io(struct backing_dev_info *bdi) |
265 | { | |
266 | return wb_has_dirty_io(&bdi->wb); | |
267 | } | |
268 | ||
03ba3782 | 269 | /* |
6f904ff0 | 270 | * kupdated() used to do this. We cannot do it from the bdi_forker_thread() |
03ba3782 JA |
271 | * or we risk deadlocking on ->s_umount. The longer term solution would be |
272 | * to implement sync_supers_bdi() or similar and simply do it from the | |
6f904ff0 | 273 | * bdi writeback thread individually. |
03ba3782 JA |
274 | */ |
275 | static int bdi_sync_supers(void *unused) | |
276 | { | |
277 | set_user_nice(current, 0); | |
278 | ||
279 | while (!kthread_should_stop()) { | |
280 | set_current_state(TASK_INTERRUPTIBLE); | |
281 | schedule(); | |
282 | ||
283 | /* | |
284 | * Do this periodically, like kupdated() did before. | |
285 | */ | |
286 | sync_supers(); | |
287 | } | |
288 | ||
289 | return 0; | |
290 | } | |
291 | ||
6423104b | 292 | void bdi_arm_supers_timer(void) |
03ba3782 JA |
293 | { |
294 | unsigned long next; | |
295 | ||
6423104b JA |
296 | if (!dirty_writeback_interval) |
297 | return; | |
298 | ||
03ba3782 JA |
299 | next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies; |
300 | mod_timer(&sync_supers_timer, round_jiffies_up(next)); | |
301 | } | |
302 | ||
303 | static void sync_supers_timer_fn(unsigned long unused) | |
304 | { | |
305 | wake_up_process(sync_supers_tsk); | |
6423104b | 306 | bdi_arm_supers_timer(); |
03ba3782 JA |
307 | } |
308 | ||
6467716a AB |
309 | static void wakeup_timer_fn(unsigned long data) |
310 | { | |
311 | struct backing_dev_info *bdi = (struct backing_dev_info *)data; | |
312 | ||
313 | spin_lock_bh(&bdi->wb_lock); | |
314 | if (bdi->wb.task) { | |
60332023 | 315 | trace_writeback_wake_thread(bdi); |
6467716a AB |
316 | wake_up_process(bdi->wb.task); |
317 | } else { | |
318 | /* | |
319 | * When bdi tasks are inactive for long time, they are killed. | |
320 | * In this case we have to wake-up the forker thread which | |
321 | * should create and run the bdi thread. | |
322 | */ | |
60332023 | 323 | trace_writeback_wake_forker_thread(bdi); |
6467716a AB |
324 | wake_up_process(default_backing_dev_info.wb.task); |
325 | } | |
326 | spin_unlock_bh(&bdi->wb_lock); | |
327 | } | |
328 | ||
329 | /* | |
330 | * This function is used when the first inode for this bdi is marked dirty. It | |
331 | * wakes-up the corresponding bdi thread which should then take care of the | |
332 | * periodic background write-out of dirty inodes. Since the write-out would | |
333 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just | |
334 | * set up a timer which wakes the bdi thread up later. | |
335 | * | |
336 | * Note, we wouldn't bother setting up the timer, but this function is on the | |
337 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches | |
338 | * by delaying the wake-up. | |
339 | */ | |
340 | void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi) | |
341 | { | |
342 | unsigned long timeout; | |
343 | ||
344 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); | |
345 | mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout); | |
346 | } | |
347 | ||
fff5b85a AB |
348 | /* |
349 | * Calculate the longest interval (jiffies) bdi threads are allowed to be | |
350 | * inactive. | |
351 | */ | |
352 | static unsigned long bdi_longest_inactive(void) | |
353 | { | |
354 | unsigned long interval; | |
355 | ||
356 | interval = msecs_to_jiffies(dirty_writeback_interval * 10); | |
357 | return max(5UL * 60 * HZ, interval); | |
358 | } | |
359 | ||
6f904ff0 | 360 | static int bdi_forker_thread(void *ptr) |
03ba3782 JA |
361 | { |
362 | struct bdi_writeback *me = ptr; | |
363 | ||
766f9164 | 364 | current->flags |= PF_SWAPWRITE; |
c1955ce3 CH |
365 | set_freezable(); |
366 | ||
367 | /* | |
368 | * Our parent may run at a different priority, just set us to normal | |
369 | */ | |
370 | set_user_nice(current, 0); | |
03ba3782 JA |
371 | |
372 | for (;;) { | |
fff5b85a | 373 | struct task_struct *task = NULL; |
78c40cb6 | 374 | struct backing_dev_info *bdi; |
adf39240 AB |
375 | enum { |
376 | NO_ACTION, /* Nothing to do */ | |
377 | FORK_THREAD, /* Fork bdi thread */ | |
fff5b85a | 378 | KILL_THREAD, /* Kill inactive bdi thread */ |
adf39240 | 379 | } action = NO_ACTION; |
03ba3782 JA |
380 | |
381 | /* | |
382 | * Temporary measure, we want to make sure we don't see | |
383 | * dirty data on the default backing_dev_info | |
384 | */ | |
6467716a AB |
385 | if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) { |
386 | del_timer(&me->wakeup_timer); | |
03ba3782 | 387 | wb_do_writeback(me, 0); |
6467716a | 388 | } |
03ba3782 | 389 | |
cfc4ba53 | 390 | spin_lock_bh(&bdi_lock); |
c5f7ad23 | 391 | set_current_state(TASK_INTERRUPTIBLE); |
03ba3782 | 392 | |
78c40cb6 | 393 | list_for_each_entry(bdi, &bdi_list, bdi_list) { |
adf39240 AB |
394 | bool have_dirty_io; |
395 | ||
396 | if (!bdi_cap_writeback_dirty(bdi) || | |
397 | bdi_cap_flush_forker(bdi)) | |
03ba3782 JA |
398 | continue; |
399 | ||
080dcec4 AB |
400 | WARN(!test_bit(BDI_registered, &bdi->state), |
401 | "bdi %p/%s is not registered!\n", bdi, bdi->name); | |
402 | ||
adf39240 AB |
403 | have_dirty_io = !list_empty(&bdi->work_list) || |
404 | wb_has_dirty_io(&bdi->wb); | |
78c40cb6 AB |
405 | |
406 | /* | |
adf39240 AB |
407 | * If the bdi has work to do, but the thread does not |
408 | * exist - create it. | |
78c40cb6 | 409 | */ |
adf39240 AB |
410 | if (!bdi->wb.task && have_dirty_io) { |
411 | /* | |
412 | * Set the pending bit - if someone will try to | |
413 | * unregister this bdi - it'll wait on this bit. | |
414 | */ | |
415 | set_bit(BDI_pending, &bdi->state); | |
416 | action = FORK_THREAD; | |
417 | break; | |
418 | } | |
fff5b85a | 419 | |
6bf05d03 JA |
420 | spin_lock(&bdi->wb_lock); |
421 | ||
fff5b85a AB |
422 | /* |
423 | * If there is no work to do and the bdi thread was | |
424 | * inactive long enough - kill it. The wb_lock is taken | |
425 | * to make sure no-one adds more work to this bdi and | |
426 | * wakes the bdi thread up. | |
427 | */ | |
428 | if (bdi->wb.task && !have_dirty_io && | |
429 | time_after(jiffies, bdi->wb.last_active + | |
430 | bdi_longest_inactive())) { | |
431 | task = bdi->wb.task; | |
432 | bdi->wb.task = NULL; | |
433 | spin_unlock(&bdi->wb_lock); | |
434 | set_bit(BDI_pending, &bdi->state); | |
435 | action = KILL_THREAD; | |
436 | break; | |
437 | } | |
6bf05d03 | 438 | spin_unlock(&bdi->wb_lock); |
03ba3782 | 439 | } |
080dcec4 | 440 | spin_unlock_bh(&bdi_lock); |
03ba3782 | 441 | |
c4ec7908 AB |
442 | /* Keep working if default bdi still has things to do */ |
443 | if (!list_empty(&me->bdi->work_list)) | |
444 | __set_current_state(TASK_RUNNING); | |
445 | ||
adf39240 AB |
446 | switch (action) { |
447 | case FORK_THREAD: | |
448 | __set_current_state(TASK_RUNNING); | |
6628bc74 AB |
449 | task = kthread_create(bdi_writeback_thread, &bdi->wb, |
450 | "flush-%s", dev_name(bdi->dev)); | |
adf39240 AB |
451 | if (IS_ERR(task)) { |
452 | /* | |
453 | * If thread creation fails, force writeout of | |
d46db3d5 WF |
454 | * the bdi from the thread. Hopefully 1024 is |
455 | * large enough for efficient IO. | |
adf39240 | 456 | */ |
d46db3d5 | 457 | writeback_inodes_wb(&bdi->wb, 1024); |
fff5b85a AB |
458 | } else { |
459 | /* | |
460 | * The spinlock makes sure we do not lose | |
461 | * wake-ups when racing with 'bdi_queue_work()'. | |
6628bc74 AB |
462 | * And as soon as the bdi thread is visible, we |
463 | * can start it. | |
fff5b85a | 464 | */ |
6467716a | 465 | spin_lock_bh(&bdi->wb_lock); |
adf39240 | 466 | bdi->wb.task = task; |
6467716a | 467 | spin_unlock_bh(&bdi->wb_lock); |
6628bc74 | 468 | wake_up_process(task); |
fff5b85a AB |
469 | } |
470 | break; | |
471 | ||
472 | case KILL_THREAD: | |
473 | __set_current_state(TASK_RUNNING); | |
474 | kthread_stop(task); | |
adf39240 | 475 | break; |
03ba3782 | 476 | |
adf39240 | 477 | case NO_ACTION: |
253c34e9 AB |
478 | if (!wb_has_dirty_io(me) || !dirty_writeback_interval) |
479 | /* | |
480 | * There are no dirty data. The only thing we | |
481 | * should now care about is checking for | |
482 | * inactive bdi threads and killing them. Thus, | |
483 | * let's sleep for longer time, save energy and | |
484 | * be friendly for battery-driven devices. | |
485 | */ | |
486 | schedule_timeout(bdi_longest_inactive()); | |
6423104b | 487 | else |
253c34e9 | 488 | schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); |
03ba3782 | 489 | try_to_freeze(); |
adf39240 | 490 | /* Back to the main loop */ |
03ba3782 JA |
491 | continue; |
492 | } | |
fff5b85a AB |
493 | |
494 | /* | |
495 | * Clear pending bit and wakeup anybody waiting to tear us down. | |
496 | */ | |
497 | clear_bit(BDI_pending, &bdi->state); | |
498 | smp_mb__after_clear_bit(); | |
499 | wake_up_bit(&bdi->state, BDI_pending); | |
03ba3782 JA |
500 | } |
501 | ||
502 | return 0; | |
503 | } | |
504 | ||
cfc4ba53 JA |
505 | /* |
506 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
507 | */ | |
508 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
509 | { | |
510 | spin_lock_bh(&bdi_lock); | |
511 | list_del_rcu(&bdi->bdi_list); | |
512 | spin_unlock_bh(&bdi_lock); | |
513 | ||
514 | synchronize_rcu(); | |
515 | } | |
516 | ||
cf0ca9fe PZ |
517 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
518 | const char *fmt, ...) | |
519 | { | |
cf0ca9fe | 520 | va_list args; |
cf0ca9fe PZ |
521 | struct device *dev; |
522 | ||
69fc208b | 523 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
c284de61 | 524 | return 0; |
f1d0b063 | 525 | |
cf0ca9fe | 526 | va_start(args, fmt); |
19051c50 | 527 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
cf0ca9fe | 528 | va_end(args); |
c284de61 AB |
529 | if (IS_ERR(dev)) |
530 | return PTR_ERR(dev); | |
66f3b8e2 | 531 | |
cf0ca9fe | 532 | bdi->dev = dev; |
cf0ca9fe | 533 | |
03ba3782 JA |
534 | /* |
535 | * Just start the forker thread for our default backing_dev_info, | |
536 | * and add other bdi's to the list. They will get a thread created | |
537 | * on-demand when they need it. | |
538 | */ | |
539 | if (bdi_cap_flush_forker(bdi)) { | |
540 | struct bdi_writeback *wb = &bdi->wb; | |
541 | ||
6f904ff0 | 542 | wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s", |
03ba3782 | 543 | dev_name(dev)); |
c284de61 AB |
544 | if (IS_ERR(wb->task)) |
545 | return PTR_ERR(wb->task); | |
03ba3782 JA |
546 | } |
547 | ||
548 | bdi_debug_register(bdi, dev_name(dev)); | |
500b067c | 549 | set_bit(BDI_registered, &bdi->state); |
c284de61 AB |
550 | |
551 | spin_lock_bh(&bdi_lock); | |
552 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); | |
553 | spin_unlock_bh(&bdi_lock); | |
554 | ||
455b2864 | 555 | trace_writeback_bdi_register(bdi); |
c284de61 | 556 | return 0; |
cf0ca9fe PZ |
557 | } |
558 | EXPORT_SYMBOL(bdi_register); | |
559 | ||
560 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) | |
561 | { | |
562 | return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); | |
563 | } | |
564 | EXPORT_SYMBOL(bdi_register_dev); | |
565 | ||
03ba3782 JA |
566 | /* |
567 | * Remove bdi from the global list and shutdown any threads we have running | |
568 | */ | |
569 | static void bdi_wb_shutdown(struct backing_dev_info *bdi) | |
66f3b8e2 | 570 | { |
03ba3782 JA |
571 | if (!bdi_cap_writeback_dirty(bdi)) |
572 | return; | |
573 | ||
574 | /* | |
fff5b85a | 575 | * Make sure nobody finds us on the bdi_list anymore |
03ba3782 | 576 | */ |
fff5b85a | 577 | bdi_remove_from_list(bdi); |
03ba3782 JA |
578 | |
579 | /* | |
fff5b85a | 580 | * If setup is pending, wait for that to complete first |
03ba3782 | 581 | */ |
fff5b85a AB |
582 | wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait, |
583 | TASK_UNINTERRUPTIBLE); | |
03ba3782 JA |
584 | |
585 | /* | |
c1955ce3 | 586 | * Finally, kill the kernel thread. We don't need to be RCU |
c62b17a5 RD |
587 | * safe anymore, since the bdi is gone from visibility. Force |
588 | * unfreeze of the thread before calling kthread_stop(), otherwise | |
589 | * it would never exet if it is currently stuck in the refrigerator. | |
03ba3782 | 590 | */ |
c1955ce3 CH |
591 | if (bdi->wb.task) { |
592 | thaw_process(bdi->wb.task); | |
593 | kthread_stop(bdi->wb.task); | |
c62b17a5 | 594 | } |
66f3b8e2 JA |
595 | } |
596 | ||
592b09a4 JA |
597 | /* |
598 | * This bdi is going away now, make sure that no super_blocks point to it | |
599 | */ | |
600 | static void bdi_prune_sb(struct backing_dev_info *bdi) | |
601 | { | |
602 | struct super_block *sb; | |
603 | ||
604 | spin_lock(&sb_lock); | |
605 | list_for_each_entry(sb, &super_blocks, s_list) { | |
606 | if (sb->s_bdi == bdi) | |
95f28604 | 607 | sb->s_bdi = &default_backing_dev_info; |
592b09a4 JA |
608 | } |
609 | spin_unlock(&sb_lock); | |
610 | } | |
611 | ||
cf0ca9fe PZ |
612 | void bdi_unregister(struct backing_dev_info *bdi) |
613 | { | |
614 | if (bdi->dev) { | |
455b2864 | 615 | trace_writeback_bdi_unregister(bdi); |
8c4db335 | 616 | bdi_prune_sb(bdi); |
6467716a | 617 | del_timer_sync(&bdi->wb.wakeup_timer); |
8c4db335 | 618 | |
03ba3782 JA |
619 | if (!bdi_cap_flush_forker(bdi)) |
620 | bdi_wb_shutdown(bdi); | |
76f1418b | 621 | bdi_debug_unregister(bdi); |
cf0ca9fe PZ |
622 | device_unregister(bdi->dev); |
623 | bdi->dev = NULL; | |
624 | } | |
625 | } | |
626 | EXPORT_SYMBOL(bdi_unregister); | |
3fcfab16 | 627 | |
6467716a AB |
628 | static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) |
629 | { | |
630 | memset(wb, 0, sizeof(*wb)); | |
631 | ||
632 | wb->bdi = bdi; | |
633 | wb->last_old_flush = jiffies; | |
634 | INIT_LIST_HEAD(&wb->b_dirty); | |
635 | INIT_LIST_HEAD(&wb->b_io); | |
636 | INIT_LIST_HEAD(&wb->b_more_io); | |
f758eeab | 637 | spin_lock_init(&wb->list_lock); |
6467716a AB |
638 | setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi); |
639 | } | |
640 | ||
e98be2d5 WF |
641 | /* |
642 | * Initial write bandwidth: 100 MB/s | |
643 | */ | |
644 | #define INIT_BW (100 << (20 - PAGE_SHIFT)) | |
645 | ||
b2e8fb6e PZ |
646 | int bdi_init(struct backing_dev_info *bdi) |
647 | { | |
03ba3782 | 648 | int i, err; |
b2e8fb6e | 649 | |
cf0ca9fe PZ |
650 | bdi->dev = NULL; |
651 | ||
189d3c4a | 652 | bdi->min_ratio = 0; |
a42dde04 PZ |
653 | bdi->max_ratio = 100; |
654 | bdi->max_prop_frac = PROP_FRAC_BASE; | |
03ba3782 | 655 | spin_lock_init(&bdi->wb_lock); |
66f3b8e2 | 656 | INIT_LIST_HEAD(&bdi->bdi_list); |
03ba3782 JA |
657 | INIT_LIST_HEAD(&bdi->work_list); |
658 | ||
659 | bdi_wb_init(&bdi->wb, bdi); | |
660 | ||
b2e8fb6e | 661 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
ea319518 | 662 | err = percpu_counter_init(&bdi->bdi_stat[i], 0); |
04fbfdc1 PZ |
663 | if (err) |
664 | goto err; | |
665 | } | |
666 | ||
667 | bdi->dirty_exceeded = 0; | |
e98be2d5 WF |
668 | |
669 | bdi->bw_time_stamp = jiffies; | |
670 | bdi->written_stamp = 0; | |
671 | ||
672 | bdi->write_bandwidth = INIT_BW; | |
673 | bdi->avg_write_bandwidth = INIT_BW; | |
674 | ||
04fbfdc1 PZ |
675 | err = prop_local_init_percpu(&bdi->completions); |
676 | ||
677 | if (err) { | |
678 | err: | |
4b01a0b1 | 679 | while (i--) |
04fbfdc1 | 680 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
b2e8fb6e PZ |
681 | } |
682 | ||
683 | return err; | |
684 | } | |
685 | EXPORT_SYMBOL(bdi_init); | |
686 | ||
687 | void bdi_destroy(struct backing_dev_info *bdi) | |
688 | { | |
689 | int i; | |
690 | ||
ce5f8e77 JA |
691 | /* |
692 | * Splice our entries to the default_backing_dev_info, if this | |
693 | * bdi disappears | |
694 | */ | |
695 | if (bdi_has_dirty_io(bdi)) { | |
696 | struct bdi_writeback *dst = &default_backing_dev_info.wb; | |
697 | ||
f758eeab | 698 | bdi_lock_two(&bdi->wb, dst); |
ce5f8e77 JA |
699 | list_splice(&bdi->wb.b_dirty, &dst->b_dirty); |
700 | list_splice(&bdi->wb.b_io, &dst->b_io); | |
701 | list_splice(&bdi->wb.b_more_io, &dst->b_more_io); | |
f758eeab CH |
702 | spin_unlock(&bdi->wb.list_lock); |
703 | spin_unlock(&dst->list_lock); | |
ce5f8e77 | 704 | } |
66f3b8e2 | 705 | |
cf0ca9fe PZ |
706 | bdi_unregister(bdi); |
707 | ||
b2e8fb6e PZ |
708 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
709 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
04fbfdc1 PZ |
710 | |
711 | prop_local_destroy_percpu(&bdi->completions); | |
b2e8fb6e PZ |
712 | } |
713 | EXPORT_SYMBOL(bdi_destroy); | |
714 | ||
c3c53206 JA |
715 | /* |
716 | * For use from filesystems to quickly init and register a bdi associated | |
717 | * with dirty writeback | |
718 | */ | |
719 | int bdi_setup_and_register(struct backing_dev_info *bdi, char *name, | |
720 | unsigned int cap) | |
721 | { | |
722 | char tmp[32]; | |
723 | int err; | |
724 | ||
725 | bdi->name = name; | |
726 | bdi->capabilities = cap; | |
727 | err = bdi_init(bdi); | |
728 | if (err) | |
729 | return err; | |
730 | ||
731 | sprintf(tmp, "%.28s%s", name, "-%d"); | |
732 | err = bdi_register(bdi, NULL, tmp, atomic_long_inc_return(&bdi_seq)); | |
733 | if (err) { | |
734 | bdi_destroy(bdi); | |
735 | return err; | |
736 | } | |
737 | ||
738 | return 0; | |
739 | } | |
740 | EXPORT_SYMBOL(bdi_setup_and_register); | |
741 | ||
3fcfab16 AM |
742 | static wait_queue_head_t congestion_wqh[2] = { |
743 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
744 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
745 | }; | |
0e093d99 | 746 | static atomic_t nr_bdi_congested[2]; |
3fcfab16 | 747 | |
1faa16d2 | 748 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
749 | { |
750 | enum bdi_state bit; | |
1faa16d2 | 751 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 | 752 | |
1faa16d2 | 753 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
0e093d99 MG |
754 | if (test_and_clear_bit(bit, &bdi->state)) |
755 | atomic_dec(&nr_bdi_congested[sync]); | |
3fcfab16 AM |
756 | smp_mb__after_clear_bit(); |
757 | if (waitqueue_active(wqh)) | |
758 | wake_up(wqh); | |
759 | } | |
760 | EXPORT_SYMBOL(clear_bdi_congested); | |
761 | ||
1faa16d2 | 762 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
763 | { |
764 | enum bdi_state bit; | |
765 | ||
1faa16d2 | 766 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
0e093d99 MG |
767 | if (!test_and_set_bit(bit, &bdi->state)) |
768 | atomic_inc(&nr_bdi_congested[sync]); | |
3fcfab16 AM |
769 | } |
770 | EXPORT_SYMBOL(set_bdi_congested); | |
771 | ||
772 | /** | |
773 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 774 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
775 | * @timeout: timeout in jiffies |
776 | * | |
777 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
778 | * write congestion. If no backing_devs are congested then just wait for the | |
779 | * next write to be completed. | |
780 | */ | |
8aa7e847 | 781 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
782 | { |
783 | long ret; | |
52bb9198 | 784 | unsigned long start = jiffies; |
3fcfab16 | 785 | DEFINE_WAIT(wait); |
8aa7e847 | 786 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
787 | |
788 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
789 | ret = io_schedule_timeout(timeout); | |
790 | finish_wait(wqh, &wait); | |
52bb9198 MG |
791 | |
792 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), | |
793 | jiffies_to_usecs(jiffies - start)); | |
794 | ||
3fcfab16 AM |
795 | return ret; |
796 | } | |
797 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 798 | |
0e093d99 MG |
799 | /** |
800 | * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes | |
801 | * @zone: A zone to check if it is heavily congested | |
802 | * @sync: SYNC or ASYNC IO | |
803 | * @timeout: timeout in jiffies | |
804 | * | |
805 | * In the event of a congested backing_dev (any backing_dev) and the given | |
806 | * @zone has experienced recent congestion, this waits for up to @timeout | |
807 | * jiffies for either a BDI to exit congestion of the given @sync queue | |
808 | * or a write to complete. | |
809 | * | |
25985edc | 810 | * In the absence of zone congestion, cond_resched() is called to yield |
0e093d99 MG |
811 | * the processor if necessary but otherwise does not sleep. |
812 | * | |
813 | * The return value is 0 if the sleep is for the full timeout. Otherwise, | |
814 | * it is the number of jiffies that were still remaining when the function | |
815 | * returned. return_value == timeout implies the function did not sleep. | |
816 | */ | |
817 | long wait_iff_congested(struct zone *zone, int sync, long timeout) | |
818 | { | |
819 | long ret; | |
820 | unsigned long start = jiffies; | |
821 | DEFINE_WAIT(wait); | |
822 | wait_queue_head_t *wqh = &congestion_wqh[sync]; | |
823 | ||
824 | /* | |
825 | * If there is no congestion, or heavy congestion is not being | |
826 | * encountered in the current zone, yield if necessary instead | |
827 | * of sleeping on the congestion queue | |
828 | */ | |
829 | if (atomic_read(&nr_bdi_congested[sync]) == 0 || | |
830 | !zone_is_reclaim_congested(zone)) { | |
831 | cond_resched(); | |
832 | ||
833 | /* In case we scheduled, work out time remaining */ | |
834 | ret = timeout - (jiffies - start); | |
835 | if (ret < 0) | |
836 | ret = 0; | |
837 | ||
838 | goto out; | |
839 | } | |
840 | ||
841 | /* Sleep until uncongested or a write happens */ | |
842 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
843 | ret = io_schedule_timeout(timeout); | |
844 | finish_wait(wqh, &wait); | |
845 | ||
846 | out: | |
847 | trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), | |
848 | jiffies_to_usecs(jiffies - start)); | |
849 | ||
850 | return ret; | |
851 | } | |
852 | EXPORT_SYMBOL(wait_iff_congested); |